Cross-linkable materials based on organosilicon compounds

ABSTRACT

Crosslinkable compositions employing organosilicon compounds having at least two hydrolyzable groups, optionally a crosslinker, and optionally a compound containing basic nitrogen, include a crosslinking catalyst which is a reaction product of a phosphorus compound, a sulfur compound, and a tin compound. The compositions exhibit improved shelf life.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The invention relates in particular to materials crosslinkable at roomtemperature and based on organosilicon compounds, e.g. so-called RTV-1materials, and special tin compounds which can be used as a catalyst inthese materials.

2. Background Art

The use of dialkyltin(IV) compounds as condensation catalysts in RTV-1and RTV-2 silicone rubbers is generally known. In RTV-1 alkoxymaterials, these tin compounds, however, have the disadvantage that theyalso catalyze the undesired cleavage of the siloxane chains by alcoholradicals (“equilibration”), terminal alkoxy groups of the polysiloxanechain forming which are no longer crosslinkable and hence sufficientcrosslinking of the material no longer being possible; i.e. with use inthe intended manner, no vulcanized product or an insufficiently stablevulcanized product is obtained. The shelf life, stated as the durationfor which the RTV-1 material can be stored, without markedly losing itsproperties, is drastically reduced by the equilibration.

The methods of choice for increasing the shelf life are to date

-   -   replacement of the tin catalyst by a titanium catalyst. The        disadvantage here is the yellow coloration of the materials,        with the result that only opaque but not translucent materials        are possible.    -   reduction in the amount of the tin catalyst.    -   use of less aggressive tin catalysts, for example tin chelate        catalysts. An excess of chelate compound, such as, for example        acetylacetonate, is necessary; however, this is volatile,        toxicologically unsafe and hazardous to health.    -   addition of alcohol scavengers which, owing to their high        reactivity, react with alcohols. This addition is, however,        expensive and generally impairs the adhesion behavior.    -   use of catalysts having Sn—O—P bonds, as described, for example,        in EP-A 850 254, which are obtained by reacting phosphoric        monoesters with organic tin compounds. However, it has been        found that the very high acid number of the phosphorus compounds        used, which have to be employed at least in equimolar amounts        relative to the tin compound or in an excess, cause adhesion        problems which are evident in particular when the adhesive        joints are in contact with water. Moreover, compounds having        Sn—O—P bonds, obtained from phosphorus diesters, are disclosed        in U.S. Pat. No. 3,525,778 and U.S. Pat. No. 3,655,705.

Dialkyldiacyltin catalysts blocked with sulfonic acid and intended forpolyurethanes are known, the activation being effected via amines. Inthis context, reference may be made, for example, to U.S. Pat. No.5,849,864 and WO99/11369, Ashland Chemical Company. Organotin-basedRTV-2 curing agents (catalyst-crosslinking agent compositions) aredescribed in DE-A 195 27 101 and may also contain organic acids asreaction time regulators, the reaction time regulators being intended toimprove the reactivity of the claimed catalyst-crosslinking agentcompositions.

The use of Sn—O—SO₂R-containing compounds, which can be prepared, forexample, from alkyltin oxides and sulfonic acids, in, inter alia,condensation-crosslinking polymer systems is described. In this context,reference may be made, for example, to U.S. Pat. No. 3,095,434 and U.S.Pat. No. 5,981,685. The use of the claimed catalysts with Sn sulfonateunits for RTV silicone systems is not described in the examples.Especially, alkoxy-RTV-1 systems with their specific problems regardingthe shelf life and the necessity of cocatalyzing additives are notdescribed.

EP-A 623 642 describes the addition of acids, including sulfonic acids,for stabilizing RTV-1 acetoxy materials if the polymers containedtherein have been prepared by anionic polymerization of cyclicstructures and, for example, phosphoric acid was used for neutralizingthe basic polymerization catalysts and the materials therefore contain,for example, alkali metal phosphates.

The use of reaction products of sulfonic acids with amines or basicfillers is known in filled RTV systems, in order to facilitate thedispersing of the fillers and to obtain an elastomer having a lowmodulus. In this context, reference may be made, for example, to U.S.Pat. No. 5,073,586 and U.S. Pat. No. 5,118,738.

SUMMARY OF THE INVENTION

The present invention pertains to crosslinkable compositions employingorganosilicon compounds having at least two hydrolyzable groups. andwhich employ unique tin catalysts which are the reaction product of atin compound and both a sulfur compound and a phosphorus compound.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

The invention relates to crosslinkable materials based on organosiliconcompounds having at least two hydrolyzable groups, wherein at least oneorganotin compound (C) is contained as a catalyst, the organotincompound (C) being obtainable by reacting phosphorus compounds (i)having C—P(═O)(OH) units and sulfur compounds (ii) having —SO₃H groupsand tin compounds (iii) containing units of the formulaR_(a)(XR′)_(b)SnX_((4-a-b)/2)  (III),in which

-   R may be identical or different and are monovalent, optionally    substituted hydrocarbon radicals which may be interrupted by oxygen    atoms,-   X may be identical or different and are —O— or —S—,-   R′ may be identical or different and are a hydrogen atom or    monovalent, optionally substituted hydrocarbon radicals which may be    interrupted by oxygen atoms, or optionally substituted silyl    radicals,-   a is 0, 1, 2 or 3 and-   b is 0, 1, 2 or 3,-   with the proviso that the sum a+b is less than or equal to 4.

Radical R is preferably a hydrocarbon radical having 1 to 18 carbonatoms, particularly preferably an alkyl radical having 1 to 12 carbonatoms, in particular the n-butyl and the n-octyl radical.

Examples of radicals R are alkyl radicals, such as the methyl, ethyl,n-propyl, isopropyl, 1-n-butyl, 2-n-butyl, isobutyl; tert-butyl,n-pentyl, isopentyl, neopentyl and tert-pentyl radical; hexyl radicals,such as the n-hexyl radical; heptyl radicals, such as the n-heptylradical; octyl radicals, such as the n-octyl radical and isooctylradicals, such as the 2,2,4-trimethylpentyl radical; nonyl radicals,such as the n-nonyl radical; decyl radicals, such as the n-decylradical; dodecyl radicals, such as the n-dodecyl radical; octadecylradicals, such as the n-octadecyl radical; cycloalkyl radicals, such asthe cyclopentyl, cyclohexyl and cycloheptyl radical and methylcyclohexylradicals; alkenyl radicals, such as the vinyl, 1-propenyl and 2-propenylradical; aryl radicals, such as the phenyl, naphthyl, anthryl andphenanthryl radical; alkaryl radicals, such as the o-, m- and p-tolylradicals; xylyl radicals and ethylphenyl radicals; and aralkyl radicals,such as the benzyl radical, and the α- and the β-phenylethyl radical.

Examples of substituted radicals R are the methoxyethyl, ethoxyethyl andethoxyethoxyethyl radical.

X is preferably an oxygen atom.

Radical R′ is preferably a hydrogen atom and hydrocarbon radicalsoptionally substituted by alkoxy radicals and/or amino radicals andhaving 1 to 18 carbon atoms, particularly preferably alkyl and arylradicals having 1 to 18 carbon atoms, in particular the methyl and ethylradical.

Examples of radicals R′ are the examples mentioned for R and themethoxyethyl, ethoxyethyl, methoxy-ethoxyethyl, aminoethoxyethyl andaminopropyl radical.

Examples of tin compounds (iii) which can be used for the preparation ofthe tin compounds (C) used according to the invention aretetra-n-butyldimethoxystannoxane, tetra-n-butyldiethoxystannoxane,di-n-butyltin oxide, tetra-n-butyldihydroxystannoxane,di-n-butyldimethoxystannane, tetra-n-octyldihydroxystannoxane,di-n-octyldimethoxystannane, octa-n-butyldiethoxytetrastannoxane,tetra-n-butyldimethoxystannoxane, tetra-n-butyldiethoxystannoxane anddi-n-butyldimethoxystannane being preferred andtetra-n-butyldimethoxystannoxane and di-n-butyldimethoxystannane beingparticularly preferred.

The phosphorus compounds (i) which can be used for the preparation ofthe tin compounds (C) used according to the invention are preferablythose of the formulaO═PR¹ _(m)Y_(n)(OH)_(3-m-n)  (I)in which

-   R¹ may be identical or different and are optionally substituted    hydrocarbon radicals having 1 to 30 carbon atoms which may be    interrupted by oxygen atoms,-   Y is —OR², —NR² ₂ or a hydrogen atom, in which R² may be identical    or different and has a meaning mentioned for R¹, or may be an    optionally substituted silyl radical,-   n is 0 or 1 and-   m is 1 or 2, with the proviso that the sum m+n is 1 or 2.

Examples of radicals R¹ and R² are, independently of one another, theexamples mentioned for radical R.

Examples of substituted radicals R¹ and R² are, independently of oneanother, hydroxyalkyl, haloalkyl and cyanoalkyl radicals and radicals ofthe structure —(CH₂CH₂O)_(z)R″, in which R″ is a methyl, ethyl or butylradical and z is an integer from 1 to 18.

Radical R¹ is preferably an aryl, alkaryl or alkyl radical, particularlypreferably an aryl or alkyl radical, in particular an octyl, benzyl orphenyl radical.

Radical R² is preferably an aryl or alkyl radical, particularlypreferably an alkyl radical, in particular a methyl, ethyl or butylradical.

Radical Y is preferably an alkoxy or aryloxy radical, particularlypreferably an alkoxy radical, in particular a methoxy, ethoxy or butoxyradical.

m preferably has the value 1.

n preferably has the value 0.

Examples of phosphorus compounds (i) are phenylphosphonic acid,benzenephosphonous acid, p-aminophenylphosphonic acid, n-octylphosphonicacid and 2-amino-8-phosphonooctanoic acid, phenylphosphonic acid andn-octylphosphonic acid being preferred.

The sulfur compounds (ii) which can be used for the preparation of thetin compounds (C) used according to the invention are preferably thoseof the formulaR³—S(═O)₂OH  (II)in which

-   R³ may be identical or different and are amine radicals bonded via    nitrogen or are monovalent, optionally substituted hydrocarbon    radicals which may be interrupted by —S(═O)₂—.

Radical R³ is preferably a hydrocarbon radical optionally substituted by—SO₃H and having 1 to 40 carbon atoms, which may be interrupted by—S(═O)₂—, particularly preferably an alkyl or aryl radical having 1 to40 carbon atoms, in particular an alkyl-substituted aryl radical having7 to 40 carbon atoms.

Examples of radicals R³ are the examples mentioned for R and —NH₂,—C₆H₄—SO₃H and —C₄H₈—SO₃H.

Examples of sulfur compounds (ii) are dodecylbenzenesulfonic acid,p-toluenesulfonic acid, benzenesulfonic acid and 1,3-benzenedisulfonicacid, dodecylbenzenesulfonic acid and p-toluenesulfonic acid beingpreferred and dodecylbenzenesulfonic acid being particularly preferred.

The compounds (i), (ii) and (iii) are each commercial products or can beprepared by processes known in organic chemistry.

The organotin compounds (C) used according to the invention may be bothstannanes and oligomeric or polymeric tin compounds, such as, forexample, stannoxanes.

The catalysts (C) used according to the invention are preferablystannanes or linear stannoxanes.

Examples of catalysts (C) used according to the invention areOct₂Sn(OP(═O)Ph(OH))(OSO₂—C₆H₄—CH₃),Oct₂Sn(O—P(═O)Oct(OEt))—O—SnOct₂(OSO₂—C₆H₄—C₁₂H₂₃),Bu₂Sn(O—P(═O)Oct(OH))—O—SnBu₂(OSO₂—C₆H₄—C₁₂H₂₃),Bu₂Sn[O—P(═O)Oct(O-Bu₂Sn(OEt))]—O—SnBu₂(OSO₂—C₆H₄—C₁₂H₂₃),Oct₂Sn(O—P(═O)Oct(OH))—O—SnOct₂(OSO₂—C₆H₄—C₁₂H₂₃),Oct₂Sn(O—P(═O)Oct(OEt))—(O—SnOct₂)₉(OSO₂—C₆H₄—C₁₂H₂₃), Oct₂Sn(O—P(═O)Oct(OEt))—O—SnOct₂(OSO₂—C₆H₄—C₁₂H₂₃),Bu₂Sn[O—P(═O)Oct(O-Bu₂Sn(OEt)]—O—SnBu₂(OSO₂—C₆H₄—C₁₂H₂₃),Bu₂Sn(O—P(═O)Oct(OH))—O—SnBu₂(OSO₂—C₆H₄—C₁₂H₂₃) andOct₂Sn(O—P(═O)Oct(OH))—O—SnOct₂(OSO₂—C₆H₄—C₁₂H₂₃) being preferred andOct₂Sn(O—P(═O)Oct(OH))—O—SnOct₂(OSO₂—C₆H₄—C₁₂H₂₃) andBu₂Sn(O—P(═O)Oct(OH))—O—SnBu₂(OSO₂—C₆H₄—C₁₂H₂₃) being particularlypreferred, in which Et is an ethyl radical, Bu is an n-butyl radical andOct is an n-octyl radical.

The present invention furthermore relates to organotin compoundsobtainable by reacting phosphorus compounds (i) having C—P(═O) (OH)units and sulfur compounds (ii) having —SO₃H groups and tin compounds(iii) containing units of the formulaR_(a)(XR′)_(b)SnX_((4-a-b)/2)   (III),in which R, X, R′, a and b have one of the abovementioned meanings, withthe proviso that the sum a+b is less than or equal to 4.

The organotin compounds (C) according to the invention or used accordingto the invention can be prepared by procedures known in organicchemistry, such as, for example, by reacting the corresponding organotincompounds with mixtures of sulfonic acids or sulfonic acid derivativesand phosphonic acids or phosphonic acid derivatives. In this context,reference may be made, for example, to A. G. Davies, OrganotinChemistry, VCH Verlagsgesellschaft, Weinheim, 1997, Section 11.3(Reactions with P-containing acids) and 11.4 (Reactions withP-containing acids).

The organotin compound (C) according to the invention or used accordingto the invention is preferably prepared by reacting the compounds (i),(ii) and (iii) at a temperature in the range from 0 to 150° C.,particularly preferably from 20 to 60° C., and at ambient pressure, i.e.from about 900 to 1 100 hPa.

In the reaction, according to the invention, the compounds (i), (ii) and(iii) phosphorus compound (i) is used in amounts of, preferably, from0.1 to 2.0 mol, particularly preferably from 0.2 to 1.0 mol, based ineach case on 1 mol of tin atoms of the tin compound (iii).

In the reaction, according to the invention, of the compounds (i), (ii)and (iii), sulfonic acid (ii) is used in amounts of, preferably, from0.05 to 1.5 mol, particularly preferably from 0.1 to 0.5 mol, based ineach case on 1 mol of tin atoms of the tin compound (iii).

The preparation of the catalysts (C) used according to the invention isalso possible in situ by direct addition of the starting materials (i),(ii) and (iii) to the other components of the crosslinkable materials,which is to be included in the disclosure of the present invention butis not preferred. If the catalysts (C) according to the invention are tobe prepared in situ, it is preferable if basic components are added onlyafter the in situ reaction of the tin compound (iii), of the sulfurcompound (ii) and of the phosphorus compound (i).

The materials according to the invention which are based onorganosilicon compounds preferably contain a compound (D) having basicnitrogen, in addition to organotin compound (C).

The compounds (D) having basic nitrogen may be amines,nitrogen-containing heterocycles or amino-functional organosiliconcompounds, the latter being preferred.

Examples of aminofunctional organosilicon compounds (D) are silaneshaving basic nitrogen, organosiloxanes having basic nitrogen, such as,for example, those of the formula (V), in which at least one radical R⁶has the meaning of a hydrocarbon radical substituted by amino groups.

The organosilicon compounds (D) having basic nitrogen are preferablythose of the formula(R⁹O)_(4-g)SiR¹⁰ _(g)   (IV),in which

-   R⁹ may be identical or different and have one of the meanings    mentioned above for R′,-   R¹⁰ may be identical or different and are monovalent; optionally    substituted hydrocarbon radicals having basic nitrogen, and-   g is 1, 2, 3 or 4,-   and the partial hydrolysis products thereof.

The partial hydrolysis products may be partial homohydrolysis products,i.e. partial hydrolysis products of one type of organosilicon compoundof the formula (IV), as well as partial cohydrolysis products, i.e.partial hydrolysis products of at least two different types oforganosilicon compounds of the formula (IV).

If the compounds (D) optionally used in the materials according to theinvention are partial hydrolysis products of organosilicon compounds ofthe formula (IV), those having up to 6 silicon atoms are preferred.

Examples of radical R⁹ are the examples mentioned above for radical R′.Radical R⁹ is preferably a hydrogen atom and alkyl radicals,particularly preferably a hydrogen atom and alkyl radicals having 1 to 4carbon atoms, in particular a hydrogen atom, the methyl radical and theethyl radical.

Examples of radicals R¹⁰ are aminomethyl, 1-aminoethyl, 3-aminopropyl,3-(2-aminoethyl)aminopropyl, aminoethylaminoethylaminopropyl andcyclohexylaminopropyl radicals.

Radical R¹⁰ is preferably a 3-aminopropyl, 3-(2-aminoethyl)aminopropyl,aminoethylaminoethylaminopropyl and cyclohexylaminopropyl radical, the3-aminopropyl and 3-(2-aminoethyl)aminopropyl radical being particularlypreferred.

Examples of compounds (D) optionally used according to the invention andhaving basic nitrogen are 3-aminopropyltrimethoxysilane,3-aminopropyltriethoxysilane,3-(2-aminoethylamino)propyltrimethoxysilane,3-(2-aminoethylamino)propyltriethoxysilane,3-(N,N-diethyl-2-aminoethylamino)propyltrimethoxysilane,3-(N,N-diethyl-2-aminoethylamino)propyltriethoxysilane,3-(cyclohexylamino)propyltrimethoxysilane,3-(cyclohexylamino)propyltriethoxysilane, aminomethyltrimethoxysilaneand partial hydrolysis products of said alkoxy-functional organosiliconcompounds.

The compounds (D) optionally used according to the invention arecommercial products or can be prepared by processes known in organicchemistry.

In addition to the organotin compounds (C) used according to theinvention as condensation catalysts and optionally used compounds (D)having basic nitrogen, the materials according to the invention maycontain all components which have also been used to date for thepreparation of organopolysiloxane materials crosslinkable at roomtemperature. The hydrolyzable groups which the organosilicon compoundsused and involved in the crosslinking reaction may have may be anydesired groups, such as acetoxy, oximato and organyloxy groups, inparticular alkoxy radicals, such as ethoxy radicals, alkoxyethoxyradicals and methoxy radicals. Furthermore, the organosilicon compoundsmay be both siloxanes (≡Si—O—Si≡ structures) and silcarbanes(≡Si—R′″—Si≡ structures in which R′″ is a divalent hydrocarbon radicalwhich is optionally substituted or interrupted by hetero atoms) orcopolymers thereof.

The crosslinkable materials according to the invention are preferablythose which contain

-   (A) organopolysiloxanes having at least two hydrolyzable radicals    selected from acetoxy, oximato and organyloxy groups, optionally-   (B) crosslinking agents having at least three hydrolyzable radicals    selected from acetoxy, oximato and organyloxy groups, and/or partial    hydrolysis products thereof,-   (C) organotin compound obtainable by reacting phosphorus compounds    (i), sulfur compounds (ii) and tin compounds (iii) and optionally-   (D) compounds (D) having basic nitrogen.

The organopolysiloxanes used according to the invention and having atleast two hydrolyzable groups (A) are preferably those of the generalformula(R⁵O)_(3-d)R⁶ _(d)SiO—[R⁶ ₂SiO]_(e)—SiR⁶ _(d)(OR⁵)_(3-d)  (V),in which

-   d is 0, 1 or 2,-   R⁶ are identical or different SiC-bonded hydrocarbon radicals having    1 to 18 carbon atoms, which are optionally substituted by halogen    atoms, ether groups, ester groups, epoxy groups, mercapto groups,    cyano groups, amino groups or (poly)glycol radicals, the latter    being composed of oxyethylene and/or oxypropylene units, and-   R⁵ may be identical or different and have a meaning mentioned for    R′,-   e is an integer from 10 to 10,000 preferably from 100 to 3,000,    particularly preferably from 400 to 2,000, with the proviso that d    may have the value 2 only when R⁵ is a hydrogen atom.

Examples of radicals R⁶ are the examples mentioned above for radical R.

Radical R⁶ is preferably an alkyl radical, particularly preferably analkyl radical having 1 to 4 carbon atoms, in particular the methylradical.

Examples of radicals R⁵ are the examples mentioned above for radical R′.

Radical R⁵ is preferably a hydrogen atom and an alkyl radical,particularly preferably a hydrogen atom and an alkyl radical having 1 to4 carbon atoms, in particular a hydrogen atom, the methyl radical andthe ethyl radical.

The average value for the number e in formula (V) is preferably chosenso that the organopolysiloxane of the formula (V) has a viscosity offrom 1,000 to 2,500,000 mPa·s, particularly preferably from 4,000 to800,000 mPa·s, measured in each case at a temperature of 25° C.

Although not shown in formula (V) and not evident from the designationdiorganopolysiloxane, up to 10 mol percent of the diorganosiloxane unitsmay be replaced by other siloxane units, such as R⁶ ₃SiO_(1/2),R⁶SiO_(3/2) and SiO_(4/2) units, in which R⁶ has the meaning mentionedabove therefor.

Examples of the organopolysiloxanes used in the materials according tothe invention and having at least two organyloxy radicals on eachterminal group (A) are

-   (MeO)₂MeSiO[SiMe₂O]₂₀₀₋₂₀₀₀SiMe(OMe)₂,-   (EtO)₂MeSiO[SiMe₂O]₂₀₀₋₂₀₀₀SiMe(OEt)₂,-   (MeO)₂ViSiO[SiMe₂O]₂₀₀₋₂₀₀₀SiVi(OMe)₂ and-   (EtO)₂ViSiO[SiMe₂O]₂₀₀₋₂₀₀₀SiVi(OEt)₂,-   (MeO)₂(H₂N—CH₂CH₂CH₂)SiO[SiMe₂O]₂₀₀₋₂₀₀₀Si(CH₂CH₂CH₂—NH₂)(OMe)₂,-   in which Me is a methyl radical, Et is an ethyl radical and Vi is a    vinyl radical.

The organosilicon compounds used in the materials according to theinvention and having at least two hydrolyzable groups (A) are commercialproducts or can be prepared by processes known in silicon chemistry, forexample by reacting α, ω-dihydroxypolyorganosiloxanes with correspondingorganyloxysilanes.

The crosslinking agents (B) optionally used in the materials accordingto the invention may be any desired crosslinking agents known to dateand having at least three hydrolyzable radicals, such as, for example,silanes or siloxanes having at least three organyloxy groups.

The crosslinking agents (B) optionally used in the materials accordingto the invention are preferably organosilicon compounds of the formula(R⁷O)_(4-f)SiR⁸ _(f)   (VI),in which

-   R⁷ may be identical or different and have one of the meanings    mentioned above for R′,-   R⁸ has a meaning mentioned above for R and-   f is 0 or 1,-   and the partial hydrolysis products thereof.

The partial hydrolysis products may be partial homohydrolysis products,i.e. partial hydrolysis products of one type of organosilicon compoundof the formula (VI), as well as partial cohydrolysis products, i.e.partial hydrolysis products of at least two different types oforganosilicon compounds of the formula (VI).

If the crosslinking agents (B) optionally used in the materialsaccording to the invention are partial hydrolysis products oforganosilicon compounds of the formula (VI), those having up to 6silicon atoms are preferred.

Examples of radicals R⁷ are the examples mentioned above for radical R′.Radical R⁷ is preferably a hydrogen atom and an alkyl radical,particularly preferably a hydrogen atom and an alkyl radical having 1 to4 carbon atoms, in particular a hydrogen atom, the methyl radical andthe ethyl radical.

Examples of radical R⁸ are the examples mentioned above for radical R,hydrocarbon radicals having 1 to 12 carbon atoms being preferred and themethyl and the vinyl radical being particularly preferred.

The crosslinking agents (B) optionally used in the materials accordingto the invention are particularly preferably tetramethoxysilane,tetraethoxysilane, tetrapropoxysilane, tetrabutoxysilane,methyltrimethoxysilane, methyltriethoxysilane, vinyltrimethoxysilane,vinyltriethoxysilane, phenyltrimethoxysilane, phenyltriethoxysilane,3-cyanopropyltrimethoxysilane, 3-cyanopropyltrimethoxysilane,3-(glycidyloxy)propyltriethoxysilane, 1,2-bis(trimethoxysilyl)ethane,1,2-bis(triethoxysilyl)ethane and partial hydrolysis products of saidalkoxy-functional organosilicon compounds, such as, for example,hexaethoxydisiloxane.

The crosslinking agents (B) optionally used in the materials accordingto the invention are commercial products or can be prepared by processesknown in silicon chemistry.

If the materials according to the invention contain crosslinking agents(B), they do so in amounts of, preferably, from 0.01 to 20 parts byweight, particularly preferably from 0.5 to 10 parts by weight, inparticular from 1.0 to 5.0 parts by weight, based in each case on 100parts by weight of organopolysiloxane (A). Inter alia, it is possible todispense with the addition of crosslinking agents (B) or to reduce theamount if, for example, compounds having at least three hydrolyzablegroups are used as component (D).

The materials according to the invention contain catalyst (C) in amountsof, preferably, from 0.001 to 5 percent by weight, particularlypreferably from 0.05 to 3 percent by weight, in particular from 0.1 to 1percent by weight, based in each case on 100 parts by weight oforganopolysiloxane (A).

The materials according to the invention preferably contain component(D).

If the materials according to the invention contain component (D), theydo so in amounts of, preferably, from 0.001 to 6 percent by weight,particularly preferably from 0.5 to 4 percent by weight, in particularfrom 1 to 3 percent by weight, based in each case on 100 parts by weightof organopolysiloxane (A).

In addition to the components (A), (B), (C) and optionally (D) describedabove, the materials according to the invention may contain furthersubstances, such as plasticizers (E), fillers (F), adhesion promoters(G) and additives (H), it being possible for the additional substances(E) to (H) to be the same as those which have also been used to date inmaterials storable in the absence of moisture and crosslinkable onadmission of moisture.

Examples of plasticizers (E) are dimethylpolysiloxanes which are liquidat room temperature and are endcapped by trimethylsilyloxy groups, inparticular having viscosities in the range from 50 to 1 000 mPa·s, andhigh-boiling hydrocarbons, such as, for example, liquid paraffins.

The materials according to the invention contain plasticizers (E) inamounts of, preferably, from 0 to 300 parts by weight, particularlypreferably from 10 to 200 parts by weight, in particular from 20 to 100parts by weight, based in each case on 100 parts by weight oforganopolysiloxane (A).

Example of fillers (F) are nonreinforcing fillers, i.e. fillers having aBET surface area of up to 50 m²/g, such as quartz, diatomaceous earth,calcium silicate, zirconium silicate, zeolites, metal oxide powders,such as aluminum, titanium, iron or zinc oxides or mixed oxides thereof,barium sulfate, calcium carbonate, gypsum, silicon nitride, siliconcarbide, boron nitride, glass powder and plastics powder, such aspolyacrylonitrile powder; reinforcing fillers, i.e. fillers having a BETsurface area of more than 50 m²/g, such as pyrogenically preparedsilica, precipitated silica, precipitated chalk, carbon black, such asfurnace black and acetylene black, and silicon-aluminum mixed oxideshaving a large BET surface area; fibrous fillers, such as asbestos andplastics fibers. Said fillers may have been rendered hydrophobic, forexample by the treatment with organosilanes or organosiloxanes or withstearic acid or by etherification of hydroxyl groups to give alkoxygroups. If fillers (E) are used, they are preferably hydrophilicpyrogenic silica and stearic acid-coated chalk.

The materials according to the invention contain fillers (F) in amountsof, preferably, from 0 to 300 parts by weight, particularly preferablyfrom 1 to 200 parts by weight, in particular from 5 to 200 parts byweight, based in each case on 100 parts by weight of organopolysiloxane(A).

Examples of the adhesion promoters (G) used in the materials accordingto the invention are silanes and organopolysiloxanes having functionalgroups, such as, for example, those having glycidyloxypropyl ormethacryloyloxypropyl radicals, and tetraalkoxysilanes. If, however,another component, such as, for example, siloxane (A) or crosslinkingagent (B), has said functional groups, an addition of adhesion promoterscan be dispensed with.

The materials according to the invention contain adhesion promoters (G)in amounts of, preferably, from 0 to 50 parts by weight, particularlypreferably from 1 to 20 parts by weight, in particular from 1 to 10parts by weight, based in each case on 100 parts by weight oforganopolysiloxane (A).

Examples of additives (H) are pigments, dyes, fragrances, fungicides,antioxidants, compositions for influencing the electrical properties,such as conductive carbon black, flame retardant compositions, lightstabilizers and compositions for increasing the skin formation time,such as silanes having an SiC-bonded mercaptoalkyl radical,cell-producing compositions, e.g. azodicarbonamide, heat stabilizers andthixotropic agents, such as, for example, phosphoric esters, and organicsolvents, such as alkylaromatics.

The materials according to the invention contain additives (H) inamounts of, preferably, from 0 to 100 parts by weight, particularlypreferably from 0 to 30 parts by weight, in particular from 0 to 10parts by weight, based in each case on 100 parts by weight oforganopolysiloxane (A).

The materials according to the invention are particularly preferablythose which contain

-   (A) diorganopolysiloxane of the formula (V), optionally-   (B) crosslinking agents of the formula (VI) and/or partial    hydrolysis products thereof,-   (C) organotin compound and-   (D) compound of the formula (IV) having basic nitrogen.

In particular, the materials according to the invention are those whichconsist of

-   (A) 100 parts by weight of polydiorganosiloxane of the formula (V),-   (B) from 0.01 to 20 parts by weight of crosslinking agents of the    formula (VI) and/or partial hydrolysis products thereof,-   (C) from 0.05 to 3 parts by weight of organotin compound,-   (D) from 0.01 to 4 parts by weight of compound of the formula (IV)    having basic nitrogen,-   (E) from 0 to 300 parts by weight of plasticizers,-   (F) from 0 to 300 parts by weight of fillers,-   (G) from 0 to 50 parts by weight of adhesion promoters and-   (H) from 0 to 100 parts by weight of additives.

The individual components of the materials according to the inventionmay be in each case one type of such a component as well as a mixture ofat least two different types of such components.

For the preparation of the materials according to the invention, allcomponents of the respective material can be mixed with one another inany desired sequence. This mixing can be effected at room temperatureand atmospheric pressure, i.e. from about 900 to 1 100 hPa. If desired,this mixing can, however, also be effected at higher temperatures, forexample at temperatures in the range from 35° C. to 135° C.

The preparation of the materials according to the invention and thestorage thereof must be carried out under substantially anhydrousconditions, since otherwise the materials may cure prematurely.

For the crosslinking of the materials according to the invention to giveelastomers, the customary water content of the air is sufficient. Thecrosslinking can, if desired, also be carried out at temperatures higheror lower than room temperature, for example at from −5° to 15° C. or atfrom 30° to 50° C. Preferably, the crosslinking is carried out at apressure of from 100 to 1 100 hPa, in particular at atmosphericpressure.

The present invention furthermore relates to moldings produced bycrosslinking the materials according to the invention.

The crosslinkable materials according to the invention have theadvantage that they are distinguished by a very long shelf life and ahigh crosslinking speed.

It was surprising that, by combining the sulfur-containing groups andthe phosphorus-containing groups, crosslinkable materials having aconsiderably improved shelf life and substantially increasedcrosslinking speed are obtained.

Furthermore, the materials according to the invention have the advantagethat colorless, translucent materials are obtained by using theorganotin compounds (C).

The materials according to the invention can be used for all purposesfor which materials storable in the absence of water and crosslinking onadmission of water at room temperature to give elastomers can be used.

The materials according to the invention are therefore excellentlysuitable, for example, as sealing compounds for joints, includingperpendicular joints, and similar empty spaces having an internaldimension of, for example, from 10 to 40 mm, for example of buildings,land vehicles, water vehicles and aircraft, or as adhesives or cementingmaterials, for example in window construction or in the production ofaquaria or glass cabinets, and, for example, for the production ofprotective coatings, including those for surfaces exposed to theconstant action of fresh or sea water, or antislip coatings, or ofelastomeric moldings and for the insulation of electrical or electronicapparatuses.

In the examples described below, all viscosity data relate to atemperature of 25° C. Unless stated otherwise, the examples below arecarried out at atmospheric pressure, i.e. at about 1 000 hPa, and atroom temperature, i.e. at about 23° C., or at a temperature which isestablished on combining the reactants at room temperature withoutadditional heating or cooling, and at a relative humidity of about 50%.Furthermore, all stated parts and percentages are based on weight,unless stated otherwise.

The shelf life of the RTV-1 alkoxy materials (=compounds) prepared inthe following examples is determined from the skin formation time of thecompounds, their vulcanization to give resilient rubbers and their ShoreA hardness as a function of the storage time. The aging of the compoundsis accelerated by storage at 100° C.

EXAMPLE 1 Preparation of Tin Catalyst 1

16 g of dodecylbenzenesulfonic acid and 6 g of benzenephosphonic acidare added to 40 g of a tin compound which was prepared by reacting 4parts of tetraethoxysilane with 2.2 parts of dibutyltin diacetate, themethanol formed being removed in vacuo. A viscous, clear compound isobtained.

In a planetary mixer having vacuum equipment, 55.4 parts by weight of apolydimethylsiloxane having —OSi(OCH₃)₂(CH₃) terminal groups, which hasa viscosity of 80,000 mPa·s, are mixed with 31.2 parts by weight of apolydimethylsiloxane having —OSi(CH₃)₃ terminal groups and a viscosityof 100 mPa·s and 4.0 parts by weight of methyltrimethoxysilane and 1.5parts by weight of 3-aminopropyltrimethoxysilane in the absence ofwater. Thereafter, 8.0 parts by weight of pyrogenic silica having a BETsurface area of 150 m²/g (commercially available from Wacker-Chemie GmbHunder the trade name “WACKER HDK® V15”) are mixed in and finally 0.15part by weight of the tin catalyst 1 described above is added. Afterhomogenization in vacuo, the compound thus obtained is filled intomoisture-tight containers and allowed to crosslink after the storagetime stated in table 1. For this purpose, the compound thus obtained isapplied in a 2 mm thick layer to a PE film and left to stand at 23° C.and 50% relative humidity. The vulcanization is assessed as good if thematerial has completely vulcanized after 24 hours.

In addition, the skin formation time is determined and the Shore Ahardness of a 6 mm thick elastomer slab which was vulcanized for 7 daysat 23° C. and 50% relative humidity is measured.

The results for the storage and vulcanization behavior are shown intable 1.

EXAMPLE 2 Preparation of Tin Catalyst 2

Di-n-butyltin oxide is refluxed in toluene with 1 mole equivalent ofp-dodecylbenzenesulfonic acid monohydrate and 1 mole equivalent ofbenzenephosphonic acid, and the water of reaction is removedazeotropically. The residue is dissolved in a littlemethyltrimethoxysilane, and a highly viscous liquid is obtained.

The procedure described in example 1 is repeated, except that 0.15 partby weight of tin catalyst 2 is used instead of 0.15 part by weight oftin catalyst 1.

The results for the storage and vulcanization behavior are shown intable 1.

COMPARATIVE EXAMPLE 1 Preparation of Comparative Catalyst A

16 g of dodecylbenzenesulfonic acid are added to 40 g of a tin compoundwhich was prepared by reacting 4 parts of tetraethoxysilane with 2.2parts of dibutyltin diacetate, the methanol formed being removed invacuo. A viscous, clear compound is obtained.

The procedure described in example 1 is repeated, except that 0.2 partsby weight of comparative catalyst A is used instead of 0.15 part byweight of tin catalyst 1.

The results for the storage and vulcanization behavior are shown intable 1.

COMPARATIVE EXAMPLE 2 Preparation of Comparative Catalyst B

8 g of benzenephosphonic acid are added to 40 g oftetra-n-octyldimethoxydistannoxane, the methanol formed being removed invacuo. The residue is dissolved in a little methyltrimethoxysilane, anda viscous, clear compound is obtained.

The procedure described in example 1 is repeated, except that 0.2 partby weight of comparative catalyst B is used instead of 0.15 part byweight of tin catalyst 1.

The results for the storage and vulcanization behavior are shown intable 1.

EXAMPLE 3

In a planetary mixer having vacuum equipment, 55.4 parts by weight of apolydimethylsiloxane having —OSi(OCH₃)₂(CH₃) terminal groups, which hasa viscosity of 80,000 mPa·s, are mixed with 31.2 parts by weight of apolydimethylsiloxane having —OSi(CH₃)₃ terminal groups and a viscosityof 100 mPa·s and 4.0 parts by weight of methyltrimethoxysilane and 0.2part by weight of a tin compound, which was prepared by reacting 4 partsof tetraethoxysilane with 2.2 parts of dibutyltin diacetate, and 0.05part by weight of benzenephosphonic acid (dissolved inmethyltrimethoxysilane) and 0.1 part by weight of dodecylbenzenesulfonicacid in the absence of water and are stirred for 10 minutes. Thereafter,8.0 parts by weight of pyrogenic silica having a BET surface area of 150m²/g (commercially available from Wacker-Chemie GmbH under the tradename “WACKER HDK® V15”) are mixed in and finally 1.5 parts by weight of3-aminopropyltrimethoxysilane are added. After homogenization in vacuo,the compound thus obtained is filled into moisture-tight containers andallowed to crosslink after the storage time stated in table 1, asdescribed in example 1.

The results for the storage and vulcanization behavior are shown intable 1.

COMPARATIVE EXAMPLE 3

In a planetary mixer having vacuum equipment, 55.4 parts by weight of apolydimethylsiloxane having —OSi(OCH₃)₂(CH₃) terminal groups, which hasa viscosity of 80,000 mPa·s, are mixed with 31.2 parts by weight of apolydimethylsiloxane having —OSi(CH₃)₃ terminal groups and a viscosityof 100 mPa·s and 4.0 parts by weight of methyltrimethoxysilane and 0.2part by weight of a tin compound, which was prepared by reacting 4 partsof tetraethoxysilane with 2.2 parts of dibutyltin diacetate, and 0.3part by weight of benzenephosphonic acid (saturated solution inmethyltrimethoxysilane) in the absence of water and are stirred for 10minutes. Thereafter, 8.0 parts by weight of pyrogenic silica having aBET surface area of 150 m²/g (commercially available from Wacker-ChemieGmbH under the trade name “WACKER HDK® V15”) are mixed in and finally1.5 parts by weight of 3-aminopropyltrimethoxysilane are added. Afterhomogenization in vacuo, the compound thus obtained is filled intomoisture-tight containers and allowed to crosslink after the storagetime stated in table 1, as described in example 1.

The results for the storage and vulcanization behavior are shown intable 1.

TABLE 1 Vulcanization good after x Skin formation Skin formation Skinformation Skin formation days time/Shore A time/Shore A time/Shore Atime/Shore A Storage at hardness after hardness after hardness afterhardness after 100° C. 0 d/100° C. 1 d/100° C. 2 d/100° C. 3 d/100° C.Example 1 7 15/21 18/19 18/18 19/18 Example 2 6 17/21 24/19 18/17 20/17Comp. example 1 3 10/21 12/9 15/2 No vulcanization Comp. example 2 315/15 18/15 28/12 30/8 Example 5 8 15/21 18/19 18/17 19/16 Comp. example3 2 25/16 23/10 80/4 No vulcanization

1. A crosslinkable material based on organosilicon compounds having atleast two hydrolyzable groups, wherein at least one organotin compound(C) is contained as a catalyst, said organotin compound (C) comprisingthe reaction product of phosphorus compounds (i) having C—P(═O) (OH)units and sulfur compounds (ii) having —SO₃H groups and tin compounds(iii) containing units of the formulaR_(a)(XR′)_(b)SnX_((4-a-b)/2)  (III) in which R are identical ordifferent and are monovalent, optionally substituted hydrocarbonradicals optionally interrupted by oxygen atoms, X are identical ordifferent and are —O— or —S—, R′ are identical or different and are ahydrogen atom or a monovalent, optionally substituted hydrocarbonradical optionally interrupted by oxygen atoms or by optionallysubstituted silyl radicals, a is 0, 1, 2, or 3 and b is 0, 1, 2, or 3,with the proviso that the sum a+b is less than or equal to 4, saidcrosslinkable material further comprising at least one amino-funtionalorganosilicon compound (D).
 2. The material of claim 1 wherein saidamino-funtional organosilicon compound (D) is an organosilicon compoundof the formula(R⁹O)_(4-g)SiR¹⁰ _(g)  (IV) in which R⁹ are identical or different andhave the meanings mentioned above for R′, R¹⁰ are identical or differentand are monovalent, optionally substituted hydrocarbon radicalscontaining basic nitrogen, g is 1, 2, 3, or 4, and the partialhydrolysis products thereof.
 3. A crosslinkable material, comprising:(A) at least one diorganopolysiloxane of the formula (V),(R⁵O)_(3-d)R⁶ _(d)SiO—[R⁶ ₂SiO]_(e)—SiR⁶ _(d)(OR⁵)_(3-d)  (V) in which dis 0, 1, or 2, R⁶ are identical or different SiC-bonded hydrocarbonradicals having 1 to 18 carbon atoms, optionally substituted by halogenatoms, ether groups, ester groups, epoxy groups, mercapto groups, cyanogroups, amino groups or (poly)glycol radicals, said (poly)glycolradicals being comprised of oxyethylene and/or oxypropylene units, R⁵are identical or different and are a hydrogen or a monovalent,optionally substituted hydrocarbon radical optionally interrupted byoxygen atoms or by optionally substituted silyl radicals, e is aninteger from 10 to 10,000, with the proviso that when d is 2, R⁵ is ahydrogen atom, (B) optionally, crosslinking agents of the formula (VI)and/or the partial hydrolysis products thereof,(R⁷O)_(4-f)SiR⁸ _(f)  (VI) in which R⁷ are identical or different andhave one of the meanings mentioned above for R′, R⁸ has the meaningmentioned above for R, f is 0 or 1, and the partial hydrolysis productsthereof, (C) at least one organotin catalyst comprising the reactionproduct of phosphorus compounds (i) having C—P(═O) (OH) units and sulfurcompounds (ii) having —SO₃H groups and tin compounds (iii) containingunits of the formula(R_(a)(XR′)_(b) SnX_((4-a-b)/2)  (III) in which R are identical ordifferent and are monovalent, optionally substituted hydrocarbonradicals optionally interrupted by oxygen atoms, X are identical ordifferent and are —O—or —S—, R′ are identical or different and are ahydrogen atom or a monovalent, optionally substituted hydrocarbonradical optionally interrupted by oxygen atoms or by optionallysubstituted silyl radicals, a is 0, 1, 2, or 3 and b is 0, 1, 2, or 3,with the proviso that the sum a+b is less than or equal to 4, and (D) acompound of the formula (IV) having basic nitrogen(R⁹O)_(4-g)SiR¹⁰ _(g)  (IV) in which R⁹ are identical or different andhave one of the meanings mentioned above for R′, R¹⁰ are identical ordifferent and are monovalent, optionally substituted hydrocarbonradicals containing basic nitrogen, g is 1, 2, 3, or 4, and the partialhydrolysis products thereof.
 4. The material of claim 3, wherein thecrosslinkable materials comprise (A) 100 parts by weight ofpolydiorganosiloxane of the formula (V), (B) from 0.01 to 20 parts byweight of the crosslinking agents of the formula (VI) and/or the partialhydrolysis products thereof, (C) from 0.05 to 3 parts by weight oforganotin compound, (D) from 0.01 to 4 parts by weight of a compound ofthe formula (IV) having basic nitrogen, (E) from 0 to 300 parts byweight of plasticizers, (F) from 0 to 300 parts by weight of fillers,(G) from 0 to 50 parts by weight of adhesion promoters and (H) from 0 to100 parts by weight of additives.
 5. A molding produced by crosslinkinga crosslinkable material of claim
 3. 6. A molding produced bycrosslinking a crosslinkable material of claim 4.